@worldsendless Most phone clients support multiple accounts. On Tusky and its derivatives, it's a two-step process:
1. swipe from the left to open the navigation panel
2. tap the profile picture of your other account
Statuses also have a menu option to "open with" your other account. This saves you the trouble of navigating to it after switching.
@worldsendless Not that I'm aware of - in the general case, a person's alts are not all guaranteed to be on the same server, so you'd need to switch webpages anyway.
There are some standalone web clients not affiliated with any particular instance, but I don't have enough experience to say if they'd work with your requirements. If you're interested, you might look into Halcyon and Pinafore, which are the two I can recall. Please do let me know what you discover, or if you come across any others! Might come in handy in future; you never know.
@worldsendless @khird
Not that I'm aware of unfortunately. Fortunately, the software on is open-source and you can request such things from the admin.
@khird I like to use my mobile Firefox as my client. Any thing here on actual sites?